基于注解和XML的AOP实现

   实现AOP功能的框架主要有Spring AOP和AspectJ，前者只能对方法进行创建joincut，而后者不仅可以对方法，还可以对字段和构造器创建joincut。

一、注解配置AOP。

public class Test {

    public static void main(String[] args) {
        ApplicationContext applicationContext = new AnnotationConfigApplicationContext(Aspect1.class);
        UserService userService = (UserService) applicationContext.getBean("userServiceImpl");
        userService.hello("cj");
    }
}

@Configuration //相当于创建xml配置文件
@EnableAspectJAutoProxy //开启自动代理，默认是基于接口的jdk动态代理
@ComponentScan(basePackages = "com.cj")
@Aspect //定义切面
public class Aspect1 {

    @Pointcut("execution(* com.cj.*.*(..))")//切入点表达式
    public void a() {//切入点签名

    }

    @Before("a()")
    public void b() {
        System.out.println("Before");
    }

    @AfterReturning("a()")
    public void c() {
        System.out.println("AfterReturning");
    }

    @AfterThrowing("a()")
    public void d() {
        System.out.println("AfterThrowing");

    }

    @After("a()")
    public void e() {
        System.out.println("After");

    }

    @Around("a()")
    public void f(ProceedingJoinPoint pjp) throws Throwable {
        System.out.println("Around");
        pjp.proceed();

    }

执行结果:

Around
Before
Hello:cj
After
AfterReturning

从执行结果可以看到，通知的执行顺序：Around->Before->After->AfterReturning

我们可以改下上面配置@EnableAspectJAutoProxy(proxyTargetClass = true)，使用cglib代理。

二、XML配置AOP

public class Test {

    public static void main(String[] args) {
        ApplicationContext applicationContext = new ClassPathXmlApplicationContext("beans.xml");
        UserService userService = (UserService) applicationContext.getBean("userServiceImpl");
        userService.hello("cj");
    }
}

public class Aspect1 {

    public void before() {
        System.out.println("Before");
    }

    public void afterReturning() {
        System.out.println("AfterReturning");
    }

    public void afterThrowing() {
        System.out.println("AfterThrowing");

    }

    public void after() {
        System.out.println("After");

    }

    public void around(ProceedingJoinPoint pjp) throws Throwable {
        System.out.println("Around");
        pjp.proceed();

    }

}

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
       xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
       xmlns:aop="http://www.springframework.org/schema/aop"
       xmlns:context="http://www.springframework.org/schema/context"
       xsi:schemaLocation="http://www.springframework.org/schema/beans
        http://www.springframework.org/schema/beans/spring-beans.xsd
        http://www.springframework.org/schema/context
        http://www.springframework.org/schema/context/spring-context.xsd
        http://www.springframework.org/schema/aop
        http://www.springframework.org/schema/aop/spring-aop.xsd">

    <context:component-scan base-package="com.cj"/>
    <bean id="aspect1" class="com.cj.Aspect1"></bean> <!--实例化切面bean-->
    <aop:config>
        <aop:aspect ref="aspect1">
            <aop:pointcut id="pc" expression="execution(* com.cj.*.*(..))"/>
            <aop:around method="around" pointcut-ref="pc"></aop:around>
            <aop:before method="before" pointcut-ref="pc"></aop:before>
            <aop:after method="after" pointcut-ref="pc"></aop:after>
            <aop:after-returning method="afterReturning" pointcut-ref="pc"/>
            <aop:after-throwing method="afterThrowing" pointcut-ref="pc"/>
        </aop:aspect>
    </aop:config>

</beans>

执行结果：